Effect of different factors on regeneration and transformation efficiency of tomato (Lycopersicum esculentum) hybrids

The current study aimed to produce rootstock material through micropropagation by developing efficient regeneration and Agrobacterium-mediated transformation protocols for three high quality commercial tomato hybrids (Felina, Siena and Don Jose) to overexpress the GmGSTU4 gene from Glycine max L. previously shown to enhance antioxidant activity. We investigated the plant growth regulators zeatin (Z) and 3-idoleacetic acid (IAA) to determine their best combination for an efficient regeneration protocol for each hybrid. The highest regeneration efficiency was observed in Felina (94.4%) with 1.0 mg/l Z and 0.1 mg/l IAA. In contrast, Don Jose (92.5%) and Siena (83.3%) performed better with 0.5 mg/l Z and 0.1 mg/l IAA. The three hybrids did not differ in micropropagation index, however, Felina showed the highest number of in vitro rooted and in vivo acclimatized plants. Factors such as the age of explant, days in pre- and co-culture and the concentrations of acetosyringone and thiamine on Agrobacterium-mediated genetic transformation were assessed. The transformation indices were 37.04% for the Felina, 13.8% for Siena and 8.33% for Don Jose. We conclude that targeted genotype-specific regeneration protocols will provide an efficient and cost effective genetic transformation system for rootstock production and further incorporation into micropropagation and transgrafting systems.